Means for attaching wheels to shafts



July 22,"1930. s. R. PUFFER 1,771,349

I MEANS FOR ATTACHING WHEELS T0 SHAFTS Filed June 15, 1925 Invent-0r; 4 Samue/ E Puffr H215 Attorney.

Patented July 22, 1930 UNITED, STATES PATENT OFFICE SAMUEL R. PUFFER, OF LYNN, MASSACHUSETTS, ASSI GNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK MEANS FOR ATTACHING- WHEELS TO SHAFTS Application filed June 15, 1925. Serial No. 37,835.

In connection with the operation of high speed shafts upon which wheels are mounted the problem of attaching the wheel to the shaft so that it will not loosen thereon and so that the stresses set up in the hub will not be excessive is a serious one. And it becomes particularly serious in the case of exceedingly high speeds as-are met with, for example, in connection with centrifugal compressors usedfor supercharging internal combustion engines, for here speeds of the order. of 20,000 to 30,000 revolutions per minute are utilized. This difliculty is further increased in cases where it becomes necessary to make such wheels easily removable instead of having them permanentlypressed or shrunk onto the shaft.

The object of my invention is to provide an improved means for attachin a removable wheel, such as the impeller w eel of a centrifugal compressor, to its shaft, and for a consideration of what I' believe to be novel and my invention, attention is directed to the accompanying description and the claim appended thereto.

In the drawing, Fig. 1 is a longitudinal sectional view of a removable impeller wheel embodying my invention ;'Fig. 2 is a transverse sectional view of a portion of the wheel shown in Fig. 1, and Fig. 3 is a view similar to Fig. 1 showing the impeller wheel mounted on a shaft. 7

Referring to the drawing, 1 indicates an impeller wheel having an axial bore 2 in 1ts hub 3, and 4 the shaft upon which it is mounted. The impeller vanes are indicated at 5 and the inlet vanes are indicated at 6. In the present instance, the inlet vanes 6 of the 1mpeller are shown as being formed separately from the impeller vanes 5 and as being carried by a separate hub section 7 which is in is attached not only to the body of the bushing due to the press fit between the bushing and the hub, but also to the flanges 10 on the bushing.

The bushing may be attached to the shaft 4 in any suitable manner. Preferably I attach it thereto by means of a series of keys 13 formed by cutting grooves in the bore of the bushing, which keys fit into grooves 14 in shaft 4. This provides astrong driving conmotion and one not affected by a slight loosening of the bushing on the shaft, or of the wheel on the bushing.

The impeller wheel fits against a shoulder 15 on the end of shaft 4, and is held thereon against axial displacement by a nose 16 which threads onto the end of shaft 4, and is held from turningby suitable means such as the wire 17. Nose 16 serves also to direct the me dium being pumped into the eye of the impeller. The outer end of bushing section 8 is threaded as indicated at 18 to'receive a tool to be used for pulling the impeller off the shaft when the machine is dismantled.

With the above described arrangement, when the shaft is running at moderate speeds, the driving force causing the wheel to rotate is obtained by the press fit between the bore 2 and the bushing comprising members 8 and 9. As the speed increases, and the severe stresses induced in the wheel by centrifugal force cause the bore 2 to expand and become loose on'the bushing comprising members 8 and 9, the force necessary to drive the wheel is taken by the pins 11 and transmitted by them to the flanges 10 and thence, to the-bushing. Since the holes 12 break through into the bore 2 of the hub of the wheel, the bore is free to excentrfugal force. The pins 11 are however a driving fit in the holes 12, thus insuring that the impeller will be centrally held with regard to the shaft when the size of the bore is increased, due to centrifugal forces, and also that a uniform driving contact will be maintained at all times between each of the pins 11 and the wheel hub 3.

accordance with the provisions of the patent statutes, I have described the principle of operation of my invention together with the apparatus which I now consider to represent t e best embodiment thereof, but I desire to have it understood that the appara- 15 tus shown is only illustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States, is In combination, a metal wheel having a hub provided with a bore and a plurality of holes in the hub parallel with the axis thereof directly adjacent to the bore and which along one side open intothe bore, a metal bushing fitted in the bore with a press fit, said bushing g havin flanges at its ends which lie against the end aces of the hub, and pins extending through said flanges and holes for attaching the bushing to the hub, whereby the hub may expand on'the bushing under the action of centrifugal force while still maintaining a driving connection between the hub and bushing.

In witness whereof, I have hereunto set my hand this 9th day of June, 1925. SAMUEL R. PU'FFER. 

